Electrical appliances are frequently misused or abused, so there is a need to prevent, in a simple and inexpensive way, the unauthorized use of an electrical tool or appliance. By way of example, if parents desire to control the watching of television by children, merely unplugging the set is not sufficient. A lock is needed to prevent the insertion of the plug into an outlet except by the person controlling the lock. Similarly, electrical power tools frequently found in the home or work environment can be improperly used by those not authorized. There is, accordingly, a need for a simple and economical device for locking electrical plugs to prevent unauthorized use or damage.
While there have been locking devices for the plugs on electrical appliances, none has been a simple padlock. Either the devices have multiple and separable parts which tend to become lost or misplaced when not in use or else the devices are complex and difficult to manufacture. For example, U.S. Pat. No. 3,662,320 shows a padlock combined with a frame and a bolt into which the plug is inserted. The padlock is not an integral part of the frame or the bolt. U.S. Pat. No. 3,539,968 similarly shows a padlock with a two piece blade safety cover. Likewise, U.S. Pat. No. 3,416,123 shows a padlock with a block and a pin, all three of which may become separated and misplaced.
U.S. Pat. No. 3,345,600 shows the combination of a padlock with a single locking device having a pin riveted to side walls, thereby preventing loss of the pins, but still there is a combination of a padlock and a locking device.
U.S. Pat. No. 3,543,544 is a locking device which does not involve a padlock. Rather, it shows a complex locking device which is difficult to manufacture and sell profitably.